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Hard Disk CD-ROM.

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Presentation on theme: "Hard Disk CD-ROM."— Presentation transcript:

1 Hard Disk CD-ROM

2 High-Capacity Disks What is a high-capacity disk drive?
A disk drive that uses disks with capacities of 100 MB and greater SuperDisk™ drive Uses a 120 MB or a 250 MB SuperDisk™ Developed by Imation HiFD™ (High-Capacity Floppy Disk) drive Uses a 200 MB HiFD™ disk Developed by Sony Electronics, Inc. Zip® drive Uses a Zip® disk that can store 100 MB or 250 MB of data Developed by Iomega Corporation built in Zip® drive

3 Hard disk installed in system unit
Hard Disks Consists of several inflexible, circular platters that store items electronically Also called a hard disk drive or a fixed disk A platter is coated with a material that allows items to be recorded magnetically on its surface The components of a hard disk are enclosed in an airtight, sealed case to protect them What a hard disk? Hard disk installed in system unit Introduction Computer Hardware Jess 2006

4 Hard Disks How does a hard disk work?
Step 1: The circuit board controls the movement of the head activator and a small motor Step 1 Step 2: A small motor spins the platters while the computer is running Step 2 Step 3: When software requests a disk access, the read/write heads determine the current or new location of the data Step 3 Step 4: The head actuator positions the read/write head arms over the correct location on the platters to read or write data Step 4

5 Hard Disks What is a cylinder?
track What is a cylinder? The location of a single track through all platters A single movement of the read/write head arms can read all the platters of data

6 Hard Disks How does access time compare for a hard disk and a floppy disk? A hard disk’s access time is significantly faster than a floppy disk The hard disk spins much faster than a floppy disk A hard disk spins constantly, while a floppy disk starts spinning only when it receives a read or write command Hard disk Approximately 5 to 11 milliseconds Floppy disk 84 milliseconds or approximately ½ a second

7 Designation for second partition on the hard disk
Hard Disks drive C Designation for first partition or for a single partition on the hard disk What is a partition? You can divide a formatted hard disk into separate areas called partitions Done by issuing a special operating system command Each partition functions as if it were a separate hard disk drive instructions, and information to improve data reliability drive D Designation for second partition on the hard disk

8 Hard Disks What utilities maintain a hard disk drive? Windows provides many maintenance and monitoring utilities for a hard disk on the System Tools submenu

9 Compact Discs CD-ROM CD-RW CD-R DVD-ROM What is a compact disc (CD)?
A flat, round, portable, metal storage medium that usually is 4.75 inches in diameter and less than one-twentieth of an inch thick Most personal computers today include some type of compact disc drive Also called an optical disc Available in a variety of formats CD-RW CD-R DVD-ROM

10 Compact Discs How does a laser read data on a compact disc?
Items are stored using microscopic pits (indentations) and land (flat areas) that are in the middle layer of the disk A laser light reads items from the compact disc Step 2 Compact disc label lens prism laser diode pit land Step 3 Compact disc label lens prism laser diode Light-sensing diode 1 pit land Step 1 Compact disc label lens prism laser diode Compact disc label lens prism laser diode Compact disc label Step 3: Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to the computer. Absence of reflected light is read as a digital signal of 0. Step 1: A laser diode shines a light beam toward the compact disc. Step 2: If light strikes a pit, it scatters. If light strikes land, it is reflected back toward the laser diode.

11 CD-ROMs What is the storage capacity of a CD-ROM?
A typical CD-ROM holds about 650 MB of data, instructions, and information Manufactures use CD-ROMs to store and distribute today’s multimedia and other complex software

12 40X 40 X 150 KB per second = 6,000 KB per second or 6 MB per second
CD-ROMs What is the data transfer rate of a CD-ROM drive? The time it takes a drive to transmit data, instructions, and information from the drive to another device Slower CD-ROM drives produce choppy images or sound Drive speed measured relative to original CD-ROM drives (150 KB per second) 40X 40 X 150 KB per second = 6,000 KB per second or 6 MB per second range of current rates 75X 75 X 150 KB per second = 12,250 KB per second or MB per second

13 CD-R and CD-RW What is a CD-R (compact disc-recordable)?
A multisession compact disc onto which you can record your own items such as text, graphics, and audio You write on the CD-R using a CD recorder or a CD-R drive and special software The CD-R drive can read and write both audio CDs and standard CD-ROMs You cannot erase the disc’s contents Most CD-ROM drives can read a CD-R

14 CD-R and CD-RW What is a CD-RW (compact disc-rewritable)?
An erasable disc you can write on multiple times You must have CD-RW software and a CD-RW drive Discs can be read only by multiread CD-ROM drives Drives that can read audio CDs, data CDs, CD-Rs, and CD-RWs Most recent CD-ROM drives are multiread

15 DVD-ROMs What is a DVD-ROM (digital video disc-ROM)?
An extremely high capacity compact disc capable of storing from 4.7 GB to 17 GB You must have a DVD-ROM drive or DVD player to read a DVD-ROM Looks just like a CD-ROM but data, instructions, and information is stored in a slightly different manner to achieve a higher storage capacity

16 DVD-ROMs What are other various DVD formats?
Digital motion picture DVD Used to play a movie on your television set or view on the computer DVD-RAM A rewritable DVD that allows you to erase and record on the disc multiple times DVD-R (DVD-recordable) A recordable DVD that you can write on once and read from many times DVD+RW A competing technology to DVD-RAM

17 Tapes What is tape? A magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost A tape drive reads from and writes data and information on a tape Older computers used reel-to-reel tape drives A tape cartridge is a small, rectangular, plastic housing for tape used in today’s tape drives

18 Tapes Where is tape used?
Used by business and home users to backup personal computer hard disks Both external and internal tape units for personal computers Larger computers use tape cartridges mounted in a separate cabinet called a tape library Three common types of tape drives

19 Miniature Mobile Storage Media
What is miniature mobile storage media? Handheld devices use miniature mobile storage media to augment internal storage Storage Capacity Device Name Type, Use Clik! Disk 40 MB Cartridge Digital cameras, notebook computers CompactFlash 2 to 256 MB Memory Card Digital cameras, handheld computers, notebook computers, printers, cellular telephones Microdrive 1 GB Memory card Digital cameras, handheld computers, music players, video cameras SmartMedia 2 to 128 MB Memory Card Digital cameras, handheld computers, photo printers, cellular telephones

20 Typical I/O Data Rates

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